WASHINGTON — Congressional Democrats, led by Sen. Dianne Feinstein of California, have reintroduced a bill that would ban assault weapons despite opposition in the Republican-led House and the reluctance of some Senate Democrats.

Feinstein wrote the original assault weapons ban, which became law in 1994 and expired in 2004. Democratic Reps. Carolyn McCarthy of New York and Ed Perlmutter of Colorado will lead the effort to push the bill through the House.

The new bill would do the following: • Ban the sale, transfer, importation or manufacturing of about 150 named firearms, plus certain rifles,handguns and shotguns fitted for detachable magazines and having at least one military characteristic.• Strengthen the 1994 ban by moving from a two- to a one-characteristic test to determine what constitutes an assault weapon.• Ban firearms with "thumbhole stocks" and "bullet buttons."• Ban the importation of assault weapons and large-capacity magazines.• Ban high-capacity ammunition magazines that hold more than 10 rounds.

The legislation would grandfather in weapons legally owned on the day of enactment and exempts more than 2,000 specific weapons "used for hunting or sporting purposes."

Feinstein said changes had been made in the new version to reflect lessons learned from the 1994 law and to keep pace with the technology of the weapons being manufactured today.

"One criticism of the '94 law was that it was a two-characteristic test that defined that, and that was too easy to work around," Feinstein said, noting that manufacturers would tweak models to remove one of the two characteristics making the gun legal. "The bill we are introducing today, it will be -- will make it much more difficult to work around by removing a one-characteristic test."

The National Rifle Association, which opposed the original ban and the attempts to revive in 2004, dismissed the bill as a misdirected effort to limit Second Amendment rights.

"Senator Feinstein has been trying to ban guns from law-abiding citizens for decades," said NRA spokesman Andrew Arulanandam. "It's disappointing but not surprising that she is once again focused on curtailing the Constitution instead of prosecuting criminals or fixing our broken mental health system. The American people know gun bans do not work and we are confident Congress will reject Senator Feinstein's wrong-headed approach."

Bill supporters said they were under no illusions it will be easy to pass the bill, which faces significant opposition in the Republican-controlled House.

"This is going to be hard; this is going to be difficult, but to honor those 20 lives and six more in Newtown, we are going to get it done," said Sen. Chris Murphy, D-Conn. Twenty children and six adults were killed in a mass shooting with an assault weapon on Dec. 14 at Sandy Hook Elementary School in Newtown, Conn.

Sen. Richard Blumenthal, D-Conn., became emotional as he recalled standing with parents outside the Newtown school who realized their children were not coming out of the school.

"I came there as a public official but what I saw was through the eyes of a parent and I will never forget the sights and sounds of that day," he said.

Police who responded to the shooting said they could not have stopped the massacre because of the assault weapon carried by shooter Adam Lanza, Blumenthal said.

Victims and relatives of other shootings also joined the lawmakers Thursday.

Colin Goddard was shot four times when a mentally ill student killed 32 people at Virginia Tech in April 2007.

"I carry three of those four bullets with me now for the rest of my life," he said. "I'm here on behalf of the 32 Hokies who didn't make it that day, and the 32 Americans, the 32 of us that are murdered by guns every single day."

President Obama supports an assault weapons ban among other gun-regulation measures he and Vice President Biden unveiled last week.